All Saints’ silky harmonies and slick grooves helped define the sound of Britain from the ‘90s onward. Listen beyond their biggest hits, though, and you’ll hear four women teasing out the boundaries of the pop-R&B genre. “All Hooked Up” combines a sinewy beat with metal-edged riffing and taunting lyrics; “Fundamental” marries its theme of romantic redemption to a glittering, gospel-tinged ballad; and “Ratchet Behavior” mashes up trap and dub.