Volatility is the property of a liquid to change phase to gas. As you know, the molecular arrangement of liquids and gases differ in the inter-spaces. The molecules of the gas is more widely distributed so they have less intermolecular forces. Therefore, a liquid with high volatility has very low intermolecular forces. This means that they could be easily separated from each other to conform to the molecular arrangement of a gas.
The parameter that is well associated with volatility is vapor pressure. Think of it this way, when the vapor pressure equals the atmospheric pressure, the liquid boils and changes phase into gas. So, we can say that a liquid with high volatility exhibits high vapor pressure. In this case, it would only take less energy for the vapor pressure to reach the much higher atmospheric pressure.
