intermolecular
The boiling points of liquid also correlate to the strength of the intermolecular forces. Recall that diethyl ether has weak dispersion forces, which meant that the liquid has a high vapor pressure. The weak forces also mean that it does not require a large an input of energy to make diethyl ether boil and so it has a relatively low normal boiling point of 34.6C. Water, with its much stronger hydrogen bonding, has a low vapor pressure and a higher normal boiling point of 100C.