The "Fancy" singer gets punk at Sonos And Pandora Present "An Evening With Charli XCX." (Getty Images for Sonos).

She looked (and played) the part of the bubblegum star, adopting the theme from the classic 90s chick flick "Clueless," but the smolder in her eye suggested something else lurking beneath the surface. On Tuesday night, a packed room of Angelenos would get more than a glimpse of her fiery spark.

Nursing cocktails in hand, the attendees buzzed in the small setting anticipating the event: Sonos Studio + Pandora Present "An Evening With Charli XCX." Now the name, for whatever reason, offered the impression that the set that was to unfold would be tame and intimate.

Intimate, yes. Tame, not as much.

Charli's wild-child energy is largely contained in her recorded tracks by the thumping bass that makes her dark electro pop so appealing. An evening with Charli would be an occasion to witness the unleashing of that energy, raw and tangible.

Much of her solo work relies heavily on electronic effect; her most popular single, "You (Ha Ha Ha)" borrows the hook from a track by U.K. producer Gold Panda. It's how her dark and impassioned sound accrued the pop label. And it's why her live performance was a departure from a presumption and therefore, entrancing and unexpected.

Shaded by a leather jacket and dark sunglasses despite the indoor venue, Charli’s initial puckered pout and gentle swaying suggested her demeanor would haughty and sexy, like the countless pop stars that have come before her. But as the jacket was shed, so was the protective and reserved layer revealing a positively bursting energy underneath.

Charli XCX channeled Joan Jett in a gold-sequin mini dress. With a mane of thick dark curls a la Slash whipping back and forth, the songstress thrashed and convulsed on stage the way a punk princess might. In front of a tough all-female band, she squeaked and grunted, pumping her first ferociously in the air.

With hardly a lapse in her sprightly routine, Charli sustained a dangerous determination and a sizzling conviction in her songs, making her performance intoxicating even to a fan who might have been anticipating an entirely different evening.

Charli didn’t abandon her pop totally, rather gliding easily between it and an edgier punk sound, created by her dynamic bassist, guitarist and drummer. Her cover of Snuffed by the Yakuza’s “Allergic to Love” (which can be found on her SoundCloud) was the thesis for her performance that night: cute with an attitude, pop with a sneer, punk with a smirk.

The persona she created, whose longevity seemed to multiply rather than deteriorate as her set progressed, seemed almost too boisterous for the space. To her credit, Charli persistently attempted to rile up her audience, urging the stiff and often restrained L.A. crowd to participate in her performance. While a solid plurality was adamant to coolly sip drinks, a thin throng at the base of her stage reveled in her aura.

The takeaway: Charli XCX isn’t your cut-and-dried pop singer (although, that could have been deduced from lines like “You’re my favorite drug, I smoke you in the club” from her single “SuperLove”). She’s got grit and she has a presence and a commanding one at that.

Just make sure to hydrate when you watch her. You’ll either complete a dance marathon, or merely by watching her, it’ll feel like it.

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