This observation is described in Trouton's Rule where it states that for most liquids, the enthalpy of vaporization divided by the normal boiling point has a value between 75 and 80.
Substances with very low boiling points like Hydrogen and Helium and hydrogen-bonded liquids like hydrides and alcohols are exceptions to this rule.
We'll see later that this is actually a measure of the change of entropy of the material undergoing the phase transition, i.e., the change in entropy depends very little on the material undergoing the phase change.