The phase change from liquid to gas by a gain of heat is called evaporation and the phase change from gas to a liquid by a loss of heat is called condensation. In this experiment, the liquid water in the bowl evaporates, forming water vapor (gaseous phase of a substance, such as water that normally exists in the liquid phase). The energy needed for this phase change came from the warm water, but in nature, with phase changes such as evaporation of water from the surface of any body of water, the energy generally comes from the Sun.