A pool fire is a type of diffusion flame where a layer of volatile liquid fuel is evaporating and burning.
The most important physical parameter describing a pool fire is the heat release rate, which determines the minimum safe distance needed to avoid burns from thermal radiation.
A feedback loop exists between the heat release rate and evaporation rate, as a significant part of the energy released in the combustion reaction will be transmitted from the gas phase to the liquid fuel, and can supply the needed heat of vaporization.
It is important that a pool fire involving a water-insoluble fuel is not attempted to be extinguished with water, as this can trigger explosive boiling and spattering of the burning material.
The boilover onset occurs as soon as a hot zone propagates down through the fuel, reaching the water and making it boil.