Volume Scatter Causing More and More Fireflies with More Samples I am trying to create a cloud of dust, and the volume scatter is creating a large amount of fireflies. However, unlike the other posts I've read, increasing the samples creates more fireflies, and as the accumulate, they create shiny, reflective spots around the edges of my mesh. I have a single spotlight and a blue background to light up the volumetric mesh, and changing lighting features such as "Casts Shadows" and "Multiple Importance" seems to have no effect. 

Here's an example of the problem with 50 samples:

one with 200:



and finally one with 500



As you can see the fireflies get more and more concentrated around the edges as the samples go up, and create weird highlights and reflections in the end. 

I will note that I am an advanced Blender user, and I am very familiar with eliminating fireflies, but these ones seem to defy logic. I've never seen a problem like this. Any help would be appreciated. Thanks, Graves.
Try increasing and decreasing the size of your spot light, to see its effect.

Consider adding a large plane with emissive light settings and a "go between" opaque plane with a hole in it to substitute for a spot light. 

Also consider setting your rendering "clamp indirect" to 0.1 or 0.2 to clean up the fireflies.