Consider the interstellar space: Far from radiations, heat, etc. You can imagine conditions equal to vacuum. At these conditions, what will be the state of water; Ice, liquid, vapours, or something else?
What I know is that in lab conditions in a vacuum flask if we do the same experiment with water: First it starts to boil, as the pressure in vacuum is almost zero. As it takes no time for the water to reach pressure equal to surrounding pressure, vapour pressure is formed easily. Water starts to boil without any rise in temperature. Second, since energy is spent in boiling all the kinetic energy is used up and the water molecules start to condense forming ice.
The question now is: What are the differences between lab conditions and interstellar space? Shouldn't the results be all the same?