Is there an LPV which ceased to vary?

I seem to remember reading many years ago - probably in 'Burnham's Celestial Handbook' - about a long period variable star which had behaved normally for many decades but had then stopped pulsating altogether. Am I remembering this correctly, and if so, which star was it, and what has it done since Burnham's was published (back in the mid- or late-1970s)? Thanks!