This doesn't fall into the History category, It should be in science. But I believe your answer is 'Liquid to Gas'
Nerdy explanation stuff:
The ability to gain energy from other atoms and move faster and move over one another easily is a characteristic feature of liquids. The atoms are loosely packed and have the property to slide over one another. The second state is gas in which the particles evaporate to break free the surface.
The change in the state is due to change in the packing of the particles. The loosely packed particles are gets evaporated when gets more energy.
I hope I was a big help here, Cheers!
