Dear engzooz;
Such a column is a device that needs a certain equilibrium for operation between the vapour that enters the column and the liquid that flows back to the balloon.
As more as you "overheat" the vapour that enters the column as more far the operation point from the equilibrium will be and the column loses dramatic of its efficiency, till finally you get a so called "breakthrough" what makes the fractionated distillation to a simple distillation or even more worse.
You may think yourself what this all will mean for the purity of the product.
Good Luck!
ARGOS++