Its end looks like a navel, which is a bellybutton
Distillate is the residue of evaporation.
belly button or navel
lavel
The navel may be infected (called navel ill), or the calf may have a hernia, something which needs to be seen by the vet to be fixed.
a dirty navel
The residue of combustion is called ash.
The solid material left in evaporating dish is called as Residue.
Residue.
slag
Ash
Residue left on your plate after eating may be called crumbs or scraps by others.