Boil some water, turn the heat off. Put naphtha in glass, submerge bottom of glass in recently boiled water.
There's no need for the heat source to be on while this is happening. I def dont recommend anything electric being on (hotplates, doubleboilers, whatever), even though people have used it, a small spark is all thats needed for big accident (and firemen will quite possibly denounce you if they see extraction stuff once they come in to put the fire out).
As this is happening, there will be more naphtha vapors, so avoid breathing it (have a mask, good ventilation, etc)