Why the dilution of solvent doesn't affect the solid phase, in comparison to the liquid phase?
Instead of "making the jump" from liquid to gas, the water molecules are trying to stack together into an ice crystal. The salt molecules again get in the way.
Think of making a solid as like stacking shoeboxes, but the shoeboxes are vibrating slightly. The higher the temperature, the more they vibrate. At some temperature (the melting point), the vibration gets so powerful that the whole shoebox stack collapses. Now imagine that instead of a stack of just shoeboxes (pure ice), you start putting golf balls in between some of the shoeboxes. Those are salt molecules. They get in the way of the ordered stack, they mess everything up, they make the stack collapse really easily. There has to be a lot less vibration (lower temperature) to stack the boxes when there are golf balls getting up in everyone's business. So the freezing point is reduced.