When lava lamps "explode" (tops pop off) how dangerous is it?

[Al Chemysto]

So I have a grande restored but who's original inner rubber stopper was lost. I performed this operation as an alternative:

https://oozinggoo.ning.com/photo/007-2?context=user

It seems to be working well, HOWEVER I do notice that the cap's top does get sucked (concave?) when cooling because of the vacuum pressure but it also inflates a bit outward when the lamp is on. Now I wouldn't worry so much if this cap fit on perfectly without having to have had to shave out a considerable amount of the rubber out to fit it over the glass. 

Now I've heard of lamps "exploding" or popping their tops off" as the heat build up so what I'm wondering is how dangerous is this? Are we talking campaign cork popping here that can "take an eye out" or put a dent int he dry wall? Or is it just a little "pop" without any messy and hot liquid bursting out?

This will ultimately determine where it might be safe to place my lamp. I really want to have just tot he right or left of my entertainment center so it's always within viewing angle.

Here's my lamp in action....

https://oozinggoo.ning.com/forum/topics/grande-goo-replacement-with...

[Don Souliere]

In my experience with goo kit converted lamps, My grandes sometimes pop off because it gets too hot. It makes a pop sound and no liquid will come out, just the cap will go a short distance and the popping sound is a little loud. on my regular size lamps i was able to use a bottle cap crimper to reseal them. So far I never have a problem. Hope this helps