Kundalini Fire?

As the life achieves an increasingly high vibration through purification and discipline, the fire of the soul, which is literally the fire of mind, causes the centers also to increase their vibration, and this increased activity sets up a contact with the protective "webs", or disks of pranic energy found on either side of them. Thus, [593] through the interplay, they are gradually worn away, so that in the course of time they become perforated, if I might use such an inadequate term. Many aspirants feel convinced that they have raised the kundalini fire at the base of the spine and are consequently making rapid progress, whereas all that they have accomplished is to burn or "rub through" the web at some point or other up the spine. 

A sensation of burning or of pain in any part of the spine, when not due to physiological causes, is, in the majority of cases, due to the piercing of one or other of the webs, through the activity of the centers allied to them. This happens very frequently in the case of women in connection with the solar plexus center, and with men in connection with the sacral center. Both these centers - as a result of evolutionary development - are exceedingly active and highly organized, for they are the expression of the physical creative nature and of the emotional body. A sense therefore of burning and of pain in the back indicates usually undue activity in a center, which produces destructive results upon the protective apparatus, and is no true indication of spiritual unfoldment and superiority. (Extract taken from "A Treatise On White Magick" by Alice A Bailey)