So, it has been noted that sometimes dwarves will gain the flashing red-and-yellow "on fire" coloration when exposed to magma... without actually being hurt/killed by it. They go about their ordinary business, including in at least some cases wading through magma. In one case, the fortress was saved and reloaded, and the affected dwarf burned normally upon reload. In the other case, the fortress was abandoned with dwarves still on nonfatal fire.
The proposal here, is for anyone to take on what happens in the second case.
Proposed Setup
Start with a volcano embark, as the previous events have been observed to occur around volcanos. Gain dwarves (invaders should probably be turned off), then save, copy the save and expose masses of them to magma at a controlled rate. If dwarves enter the "Everburning" state, one copy of the fortress will be saved and reloaded, to observe if everburning dwarves always become regular burning dwarves in these circumstances. Another copy will be abandoned with as many dwarves as possible in a confirmed everburning state. Before abandonment, the names of all everburning dwarves will be noted.
From the abandoned save, Legends will be checked to ensure everburning dwarves are not considered already dead, and if not a new fort will be founded. Each migrant will have his/her name checked against the list of everburning abandoners until one or more appear.
If the formerly everburning dwarves arrive in their new home healthy, or if they combust normally on entering the map, science is done.
If the formerly everburning dwarves arrive in the "everburning" state, the fort must be saved and reloaded, to establish whether or not dwarves that arrive on the map on fire will combust ordinarily when a save is loaded. If they do, we can consider science done.
If they do not, however, and remain "burning" and magma-resistant through reloads, a community effort to create, then attract a ‼Monarch‼ may be in order
I might embark on this task myself... but it's a tall order, and I'm not a particular dwarf engineering or science genius