Can anyone shed more light on the idea that they can "explode" please?
I'm am aware they can leak from the top, or if they perish they can seep from anywhere, and they can burst if perished or under pressure (like the poster above who sat on hers, they're never going to survive that). And I know if you don't expel the air then the air can expand and this can contribute to them bursting.
But, exploding, no.
I have a temperature controlled kettle so I know I only fill mine at 85deg, and I put an inch of cold water in first too. And I expel the air bubble at the top. And it has a cover. And I buy new ones pretty regularly.
I'm aware that 85deg water would still cause a bad scald if it came into contact with the skin.