Key Aspects of Boiling Vinegar/Water:

Evaporation Process: While water evaporates more readily, acetic acid also vaporizes, resulting in a strong smell of vinegar filling the air.

Concentration: If four cups of vinegar are boiled down to one cup, the resulting liquid is not simply four times as concentrated, because a significant amount of acetic acid also evaporates.

The boiling point of typical household vinegar (4-6% acetic acid) is just above water, at approximately 100.6∘C.

..