Naphtha is a combination of organic non-polar petroleum distillates. The reason naphtha can pull the freebase DMT from the basified solution is because freebase DMT is non-polar itself.
Good quality naphtha evaporates clean, meaning that it leaves no residue after complete evaporation. Before you use any naphtha make sure that you have a good quality brand. To test the quality of your naphtha evaporate a small amount in a Pyrex dish to see if it leaves no residue, if it leaves a residue then don't use it but get another brand and test that one until you find a brand with a good quality.
Naphtha is harmful to the environment. Because of this it is best not the evaporate the naphtha but to use a crystallization tek in order to reuse the naphtha. Instead of naphtha it is also possible to use D-Limonene as a non-toxic alternative.