If you have three prior misdemeanor DUI convictions within the past ten years, a new DUI can be charged as a felony.
If you have a prior theft-related conviction and served any jail time (even a brief "book & release" where you were fingerprinted and photographed, and released a couple of hours later), a new petty theft can be charged as a felony.
If you have a prior conviction for indecent exposure, Penal Code 314, any subsequent indecent exposure can be charged as a felony.
Those are just three examples that immediately came to my mind. There are probably more that I've overlooked.
Unless there are specific statutes like those, multiple misdemeanors don't just turn into a felony.