Cryonosis

First guess would be the juice, as noted earlier the middle warms the fastest and that will be were the gunk will start to form. That gunk will then cause that particular section to get hotter as it's now no longer cooling as well as the rest of the coil causing the middle to burn.

+1 from me, would be nice to slow things down a bit I will say adjusting the increments up to .5 from the default .1 helped out a lot though!

Looks like these settings right here are what you want: