The reason it behaved strangely before dissolving; DMT melts at temperatures before those of simmering water (~45°C). There's no harm in this and it probably dissolves a bit faster, but I would not recommend you heat the water any further to prevent it from boiling. This is not something you often have to worry about, but keep in mind that it boils before water. The gunk keeps getting uglier because the DMT dissolves before those not so nice impurities. For heating a recommend those USB cup-heaters, perfect for small containers and the temperatures are often good.
Just keep stirring, it takes a while to make a saturated solution!
There's a clear difference between what I say I do and what I actually do perform.