Melting point: 388.36 [115.21 °C (239.38 °F)] K Other elemental information can be found at http://www.webelements.com/
Assuming even heat distribution, and solid does not begin to melt until it reaches its melting point. Then it requires additional heat input (different for each element and molecule) to make the transition from solid to liquid. ONLY when all of the compound is in the liquid phase will its temperature again begin to rise.
The approach, transition and passing of the boiling point is similar, but with different values for the heat of transition.