Oh, I just realized you're talking about actually shooting stuff out when you fire it.
A few things that could be:
1. Water. If you've cleaned the thing recently on got it wet, that stuff'll pop when it gets hot.
2. Too much juice. If you flood the wick, some of that juice will boil... that's the popping.
3. Loose coil. I don't think this is your problem based on the pictures, but a loose coil can cause this, too, as drops of juice get between the coil and the wick.
If you've been tilting to get the juice to the top of the wick, you may just need to to less of that.