Is there a name for the opposite reaction to the dissolution? When atmospheric $\ce{CO2}$ reacts with water to form $\ce{H2CO3}$, this is called dissolution, isn't it? What term would you use for the opposite reaction when it occurs at atmospheric pressure (e.g. due to temperature change)? For a solid it would be precipitation, but here it is for a gas.
Effervescence if there are bubbles and 

Degasification more generally speaking.

There is also the term outgassing, but that term is broader than just gas coming out of liquid solution.