Why doesn a pure liquid in a distilling flask….?
because of a little fact called “phase change” Just because a liquid has enough energy to boil, that in itself does not have enough energy to phase change from liquid to a gasous state. If by chance the energy is sufficent to bring the amount of liquid to boil and the extra energy to phase change you would achieve that instant vaporization. Remember though, safety first and stand back if you plan on this action.