Some chemicals may gradually decompose during storage.  The release of decomposition by-products and consequently, the pressure buildup inside the container may cause a serious explosion.

Take formic acid as an example, prolonged storage of 98 - 100% formic acid may lead to the rupture of glass container due to the gradual decomposition of formic acid into carbon monoxide and water. 

List of Chemicals which are susceptible to internal pressure buildup during storage