Sent by RB
Editor: Wow! I've only ever heard of this happening when people forget to poke holes in the potato. I wonder if it's the particular kind of potato you're using? Even if you're using the same brand, maybe it's something in the most recent batch. That's a total wild guess, though!
Readers, do any of you have an idea what might be going on?
Related: How to Bake a Potato in the Oven