Utilizing the Iwarp tool i got this effect.
You have to copy and paste the tops (about 1 inch) of the candles then select new layer button to anchor them directly in the same position.
Otherwise the image in Iwarp is too small to really see what you are doing.
What i did was copy the left bottom three to their own layer and the right bottom three tops too their own layer and the middle candle top by itself in its own layer.
Now just open each one in Iwarp and drag with the below settings to create drips.An even better setting would be to use a smaller amount value and create small drips along the very top and then drag a few down. Be sure and bulge the top out where the candle wax collects before it drips over the edge.
I hope that helps you. At least you get the idea of one way it can be done in Gimp.