Cleaning Burnt Sugar etc. from a Pot: What Actually Works

Back in early November, I was making a tangy mustard sauce for pork and completely forgot about it.  I went into another room while the sugar, mustard powder, egg, and vinegar boiled away for about half an hour, until all that was left was what looked like a ruined pot.  We tried everything to get the pot clean, turning to Google for all the answers.

Boiled water, soapy water, baking soda, vinegar, peroxide, scrubbing with a metal scouring pad, and every combination of those, plus a few more tricks I am probably forgetting, and nothing worked.  We thought we'd have to throw the pot away for sure. 

So, then it got to be December, and I was frustrated with the darn pot.  I put some water in it, put a lid on it, and let it sit, figuring I'd worry about it after Christmas, and if I couldn't find a solution, then we'd shop for a new pot in January. 

Well, as luck would have it, the plain old water, sitting for weeks, was exactly the trick!  Nothing fancy - no boiling needed - no scrubbing - just good old water, and patience.

After eventually taking the lid off of the pot, we saw this floating in there:

It lifted right out, and the bottom of the pot was as good as new. 

Water is magic!

Have you ever had to replace a pot or pan because you burned something so badly?