Carbon dioxide - the gas that forms the bubbles in soda - stays in solution better in cold water than it does in warm water. The gas that can't stay in solution will come out as bubbles when the soda is poured. That means a freshly opened warm soda will foam up more when poured into an empty glass than a cold soda will, according to James Cragin, a U.S. Army chemist in Hanover, N.H., who has dabbled in experiments with carbonation.