The naptha hadn't been reduced yet. It was about 400 mL, so I don't think there is any way it could have been saturated, unless I am very lucky.
What concerns me is the possibility of something being dissolved in the naptha from the sodium carbonate? I don't think this is possible but it is all I could think of as to why the water would turn milky only after being mixed with Na2CO3.
The solution is still being reduced, and freeze precipitation will be attempted later today.
All future attempts will utilize distilled water, just in case.
Thanks for your replies, I will keep you updated.
[EDIT 2: A friend of a friend who was having the same problem as me sent me pictures of his freeze precipitation results. I have attached the pictures. Do those look right? I didn't expect the crystal formations to be round like that. There is still a small layer of naptha in that dish by the way. ]
khazoth attached the following image(s):

crystals1.jpg
(70kb) downloaded 59 time(s).
crystals2.jpg
(71kb) downloaded 60 time(s).Everything that I (khazoth) write on these forums is pure fiction. I write these things in a role-playing attempt to live a life more interesting than my own.