Sounds like the exact same problem I faced. By blue/yellow ended up doing the same thing. Wonder if they had issues w/ that formula or something, like it separated or something over time. When I first got my 2 they both worked great, then they sat unused a few years and this is what the blue/yellow did. The purple/yellow one works great still, but for some reason needed a bit more heat than it used to. Both used to run great dimmed to about 80%, now I had to put a socket extender on to get the purple/yellow to flow. I also tried that w/ the blue/yellow but it didn't make any difference. The only thing it'd do after hours of the small blobs was gush to the top a few times then overheat and just ball up and sit in the middle of the lamp in 1 big lump.
Wow what a difference in flow that coil made!! I might try that with a 32oz I have that gets those damn liquid bubbles too.
Yea I'm still a bit nervous myself the w/ the bulb extender, but I made sure the bulb is not touching the bottom of the globe (Just adding the extender put it just at the bottom of the globe, it might have just been touching), so what I did was remove the socket and the post holding it, and pounded down the middle section of the base, that was kind of bent upward about 1/2 inch. I pounded a dimple into it where the socket post bolts to the bottom, effectively lowering the entire thing by about 1/2 inch. Then w/ the extender on again I know its not touching the globe. It's close, but not touching. Hopefully it won't crack. If it does I'm in for not only a hell of a mess, but probably the end of my lava lamp hobby.