Liquid -> Solid As you cool a liquid, the particles move less and come closer together until it is no longer a liquid. This process is called freezing.
Liquid -> Gas As you heat a liquid, the particles kvpe more and spread out until it is no longer a liquid. This process is sometimes called boiling, and other times is called evaporation.
Solid -> Gas Solid turning into gases without becoming a liquid requires for the solid particles to gain a huge amount of energy quickly to increase their kinetic energy . This process is called sublimation.