Condensing

verb

1. To concentrate toward the essence by making more close, compact, or dense, thereby decreasing size or volume.

   "An abridged dictionary can be further condensed to pocket size."

2. To transform from a gaseous state into a liquid state via condensation.
3. To be transformed from a gaseous state into a liquid state.

   "Water condenses on the window on cold days because of the warm air inside."