Linked from
The 15 pages that link to Deliquescence, each with the reason it gives.
HumidityRelated: Humidity controls whether deliquescent salts remain dry or form a solution.
DesiccantRelated: Calcium chloride desiccant can deliquesce as it draws water from air.
LyeRelated: Solid lye absorbs moisture from air, complicating storage and measurement.
Coprinus comatusRelated: The shaggy inkcap’s cap breaks down into black liquid as it matures.