Drum with waste burst
A waste drum pressurized and "unzipped"
The drum contained chlorinated organic carbonate and sodium hydroxide solution
R-CHCl-O-CO-O-CRRR + NaOH
Subsequent checks showed that the reaction was only marginally exothermic, but was found to be extremely pH dependent, and not surprisingly generates gas. The drum used would "unzip" below 20 psi.