Components of a binary mixture of two liquids $A$ and $B$ were being separated by distillation. After some time,the separation of components stopped and the composition of the vapour phase became the same as that of the liquid phase. Both the components started coming in the distillate. Explain why this happened.

(N/A) When the composition of the liquid phase and the vapour phase becomes identical,the mixture is known as an azeotrope or a constant boiling mixture.
At this point,the mixture boils at a constant temperature without any change in composition.
Therefore,further separation by fractional distillation is not possible because the components cannot be separated based on their boiling points once the azeotropic composition is reached.