I use Esbit tabs with a 600 Ti mug to heat my water. Hate the brown gunk that sticks to the bottom of my mug. I found the perfect method to clean my pot. After the pot cools, I rub with an alcohol swab that contains 70% Isopropyl Alcohol. This melts the gunk away and liquifies it. A single square of TP wipes the pot completely clean!!!!!
These swabs are the types used by diabetics to prepare for injection - you can get 100 for about $1.00 at Walgreens.