I was just about to start preparing our supper and was rummaging in the cupboard. As I moved a tin of beans, it suddenly exploded with an enormous bang that temporarily deafened me. After a few moments, I went back to see what had happened. Suddenly a second tin exploded with no warning. I may have touched it, but not in any forceful manner. A third tin also went. 

We live in an old farmhouse without air-conditioning and it has been very warm in this weather, but nothing that should be causing this kind of effect. The temperature in the cupboard may be around the mid-thirties, but no higher than that. The affected tins are from Countdown. They have the tab-top openers but the explosions blew the entire lids off right around the seam, like they had been neatly done with a tin opener. The brand is a house one, Oak baked beans. Anyone who has these, especially at higher temperatures, should exercise extreme caution with them. They are dangerous! My hearing still hasn't completely returned to normal. The force of the explosion could also easily put someone's eye out, though fortunately there was no other injury in this case. 

I inspected (from a safe distance) some unexploded cans and they are bulging noticeably. Explosive danger aside, these can't be safe to eat. That is why I am posting this warning here and also why I am putting it in this forum. Can anyone tell me where and how I should report this further? It needs to get out as soon as possible.

Apart from the danger aspect of the food, there is also a liability one. I can't prove I bought these from Countdown, or when I did, though it wasn't years ago, but that is definitely where I got them. So I would also appreciate advice on how to pursue this matter with them, but the safety aspect is the one that needs immediate attention.