During the five years between Sucker and her self-titled official third album, Charli XCX was busier than ever exploring the different sides of her music. Not only did she found her own label, Vroom Vroom, she wrote songs for and collaborated with a who's who of pop music. She also released two mixtapes, Number 1 Angel and Pop 2, that reflected her mercurial talent -- and her connections to pop's underground and mainstream -- better than either True Romance or Sucker did. With Charli, she attempts to capture the spontaneity of those releases in a more polished format; more often than not, she succeeds. This is especially true of the collaborations that dominate the album's first half, where she's joined by some of pop's best and brightest. "Gone," which teams Charli with Christine and the Queens, is a standout that combines the crisp, double-jointed synth pop of Chris with Charli's flair for pop fantasies into a bold '80s fever dream tailor-made for dance-offs. On "Cross You Out," Charli recruits Sky Ferreira, who expertly adds some extra drama to its hyperreal heartache. The album's timeliest assist comes from Lizzo, whose irrepressible cameo on "Blame It on Your Love" helps distinguish it from the many other tropical and dancehall-inspired songs released in the late 2010s. However, it's Charli's two songs with Troye Sivan that establish the album's sound and vision. On "1999," the duo delivers an unabashedly nostalgic love song to pop's past, singing the praises of Britney and Michael over brittle synths that evoke Max Martin's heyday; later, they close the album with "2099," a darkly gleaming track that, thanks to the fractured production of PC Music's AG Cook, sounds like the landing of a spaceship -- or a time machine. Cook and other members of the PC Music collective ensure that Charli never becomes too straightforward, particularly on "Shake It," which features frantically sloshing and clanking tones that match the feverish energy of Big Freedia, CupcakKe, Brooke Candy, and Pabllo Vittar. In comparison to the album's numerous collaborations, Charli's solo tracks feel separate, and sound much lonelier. Though "Thoughts" and "I Don't Wanna Know" prioritize a mood of late-night regret over hooks, Charli saves two of the album's best songs -- the bittersweet "White Mercedes" and the tentatively hopeful "Official" -- for herself. While Charli gives equal time to her pop bona fides and her experimental leanings in a way similar to Number 1 Angel or Pop 2, it doesn't always join these facets of her music as effortlessly. In a way, its unevenness is only fitting for an artist as committed to blurring pop's artistic boundaries and connecting the dots between its past, present, and future as she is -- that she's this hard to pin down this far into her career is exactly what makes her a continually intriguing talent. ~ Heather Phares