Most often, thicker liquids take longer to boil. Viscosity and boiling point are both physical properties that are determined by intermolecular forces. Although viscosity and boiling point do not directly affect each other, there is a correlation based on the strength of these intermolecular forces.
Boiling point is the temperature at which a liquid turns into a vapor. This phase change from liquid to vapor occurs because the heat breaks apart intermolecular bonds that exist between the liquid molecules. When these molecules separate they vaporize. Stronger intermolecular forces require more heat to break.
The viscosity of a fluid is a measure of its resistance to flow or movement. The more viscous a liquid, the more resistant it is against flow, according to Allan Harvey of the National Institute of Standards and Technology. This resistance is also due to intermolecular bond strength between liquid molecules - the higher the bond strength, the higher the viscosity.