high vapor pressure: more molecules escaping the liquid phase creats a higher vapor concentration, and pressure.
P=(N/v)RT N/v is the vapor concentration of the substance
Why does a compound with a high vapor pressure boil at a lower temperature than a compound with a lower vapor pressure?
2 answers
The higher the vapor pressure rating the more quickly the solution will volatilize so the lower the boiling point. Conversely, the lower the rate the more slowly it evaporates so the boiling point is higher.