Tubes and their problems


I thought since I am currently having a few tube problems, and since i am not
that technically inclined, I would ask what are the typical warning signs and problems of our beloved tubes.
I will start off with the "popping" sound that I believe indicates either tube failure or impending failure ( perhaps someone can clarify why a tube does this?) What are the other various warning signs to look out for?
128x128daveyf
I heard popping from my Jolida FX-10's tubes on my right speaker. To see if it was the tubes, I swapped all the tubes from left and right channel and visa versa. The popping then happened on the Left side.

This proved it was the tubes - I went ahead and replaced all of them, fixing the problem.

If you do the swapping as mentioned above, and the popping continues on the same channel, then it's Not the Tubes.
The idea that a microphonic tube is one that is going to blow is incorrect. Microphonics is a construction issue but not an indication of imminent failure.

@ Joeylawn, its likely that only one of the tubes you replaced was actually the one giving you troubles. To find it, swap the tubes left for right one at a time rather than the whole bunch.
Atmasphere, you're right, but I just went ahead and replaced all 6 tubes (which were Electro Harmonix and Tung Sol) with matched and cryo'd JJ's.
Before I take out the many screws to get at my tubes I decided to buy a new rectifier before diving in. I'm hearing a very low thump, or thud, intermittently, and irregular when it shows. The two 6sn7 driver tubes are Shuguang Black Treasure which are only a few months old. Not sure which is the problem, but will switch out the rectifier first since I'm unsure of its age. (Mullard)
Every time when I replaced microphonic tube by new one the microphony of amp dissapeared.