The water evaporates and the salt remains in the beaker
It really depends on what you are trying to find out. If you want to know the effect of salt on the boiling point of water, then the answer is that salt water will boil at a higher temperature than pure water. So we can say that salt increases the boiling point of water, which is normally 100 degrees C.
If you just want the observations of boiling salt water, then the answer is that as the water is boiling, it evaporates into the atmosphere as water vapour. So we actually lose water from the beaker (or whatever you are boiling the water in) into the air. If you boil it long enough, the water will eventually be lost altogether and you'll be left with dry salt crystals on the bottom and sides of the beaker.