Is heat still being added to a liquid at the boiling point?
Yes. Heat is being added at the boiling point of a liquid.
There is though, an important difference between the effect of adding heat at a lower temperature and the effect of the addition of heat at the boiling point.
This difference is that at a lower temperature the addition of heat results in an increase in the temperature of the liquid. This increase continues till the boiling point is reached.
At the boiling point when heat is added, it does not cause an increase in the temperature of the liquid. Instead, the heat is used by the liquid to change state to gas. The heat required for a change in state from liquid to gas is called the heat of vaporization of the relevant substance.