Certain substances which are so hygroscopic, when exposed to the atmospheric air at ordinary temperatures, absorb enough water and get completely dissolved. Such substances are called deliquescent substances and this property is called deliquescence.
Deliquescent substances lose their crystalline shape and ultimately dissolve in the absorbed water forming a saturated solution.
Deliquescence is maximum when:
1) The temperature is low
2) The atmosphere is humid
Examples: Calcium chloride (CaCl2), Caustic soda (NaOH), Caustic potash (KOH) and Ferric chloride (FeCl3).