Remember Pop Rocks, the tiny pieces of carbonated sugar that sat in your hand and sizzled in your mouth? Big Dipper plays that sort of pop rock: On record the band lies colorful and insignificant, but apply a little human flesh to it (ninety-five-percent water) and it snaps and zings. Slam, the Dips' major-label debut after three indie releases, is the product of an all-out effort to crystallize...