Notice in the following graph how the temperature levels out during the melting and boiling processes. For example, our ancestors were able to boil water in bark containers because the temperature of the pot would never exceed 100 oC. The container would char a bit but not burn.
actual amount of heat that has to be added to change a solid substance to a gas
depends on the following four properties.
1. Specific Heat of the Substance
2. Total Mass of the Substance
3. Heat of Fusion of the Substance4. Heat of Vaporization of the Substance.