What is the purpose of continuing to heat a substance after it reaches a temperature plateau?

They are changes in bonding energy between the molecules. ... Immediately after the molecular bonds in the ice are broken the molecules are moving (vibrating) at the same average speed as before, so their average kinetic energy remains the same, and, thus, their Kelvin temperature remains the same."

Explanation:

Physical change: Generally, there is a change in state, shape or size with no formation of any new substance. These changes are reversible in nature.

Chemical change: Generally, there is a formation of any new substance. These changes are irreversible in nature.

Observation 1 : Water droplets form on the inside of the glass lid.

This means that water vapors produced from the heating of the water are get converted into liquid state that is into water.

This process of the conversion of gaseous phase into liquid phase is known as Condensation.

Since, only state of the substance is changing which means that it is a physical change.

Observation 2 : Bubbles rise as the water starts boiling.

This is is because when water starts boiling , molecules of water started getting converted into gaseous state that is into water vapors.

This process of the conversion of liquid phase into gaseous phase is known as Evaporation.

Here also only state of the substance is changing which means that it is also a physical change.