Country singer Cam broke through in 2015 with “Burning House,” a subdued but smoldering ballad that defied modern notions of how women in Nashville could succeed. Untamed builds on that chemistry, blending earthy arrangements and firm, folksy sentiments into a style that sounds progressive without being too pop and traditional without being too retro. It’s an approach that turned artists like Shania Twain into titans in the '90s, and as handy as Cam is with emotional anvils like “Mayday” or “Cold in California,” she’s just as good with songs like “Country Ain’t Never Been Pretty,” a crass-talking kiss-off anchored by the punch line, “If your head’s on straight, your hair will be fine.”