I had a 1 lb container of H322 go bad that I bought in the late 80s. It was made in the 70s judging by the container shape and labeling. The container itself had swelled noticeably and nitric acid smelling fumes drifted out when it was opened. I poured some into a tub of tap water and it reacted by bubbling so I'm certain it was acid reacting with the alkalinity in the water. I neutralized the rest of the bottle and disposed of it.
For what it's worth, the second identical container I bought with it was just fine and was used up with no incidents.