Expand the Contents Details tab from Attribute Editor and then expand the Density tab in-order to set the numbers like the image below.
Step 16 :
Scroll down to find the Shading tab and expand it and set the Glow Intensity to 1, or what ever you would like your texts to reflect the glow.
Step 17 :
Now that we are done, set your frames to 200 then hit play. You should now see your text melting and then dissipating slowly like smoke. These 2 renders are just to show you how its looks like after rendering.