The best way for a newcomer to quickly make a dent on the charts is to drop a few tunes that have irresistible refrains or choruses. The sunny West Coast chanteuse Colbie Caillat has done just that, and her “Bubbly” is racing to the top end of the standings. One of our You Oughta Know artists, Caillat wooed MySpace users last year, and now her Coco is turning lots of heads. “Bubbly” is sweet little tune, and the chance to hear it in a stripped down setting has arrived. We’re launching Colbie’s “Unplugged” performances tomorrow. Here’s a look at one clip from the session to whet your appetite.