How does vapor pressure cause a liquid to boil?

A liquid boils when its vapor pressure becomes equal to the pressure exerted by the surrounding environment.12

At any given temperature, a liquid partially vaporizes into the space above it until the pressure exerted by that vapor reaches a characteristic value known as the vapor pressure. Because vapor pressure increases as temperature rises, heating a liquid increases its tendency to transition into a gaseous state.213

When the liquid is heated to the point where its internal vapor pressure matches the external atmospheric pressure, the liquid reaches its boiling point. At this stage, bubbles of vapor form within the bulk of the liquid and rise to the surface, marking the transition from a liquid to a gas. In the context of separation and purification, this process is the fundamental principle behind distillation, where substances are separated based on their differing boiling points.23