What makes a soda explode?

the pressure in the bottle does not increase when you shake it, but is still to blame for the phenomenon. In an unshaken bottle, soda occupies the bottom nine-tenths of the container, with a pocket of gas siting on top; this gas escapes with a pfffffft when you open the bottle, leaving the soda undisturbed. When you shake up the bottle, though, some of that carbon dioxide is mixed into the liquid and forms tiny bubbles. The gas still wants to escape when you open the bottle, though, but now has to muscle its way up through the soda toward the spout. In doing so, it pushes the liquid upwards, causing it to gush out of the bottle. The more you shake the bottle, the more thoroughly the carbon dioxide mixes with the soda, the greater the subsequent explosion.