your mother throws these trantrums becaus you ignore her as you said, and she knows that by doing this she will eventually make you give in and pay attention to her. its the same with young children, if their mum or dad doesnt pay them enough attention they have tantrums, and the way to stop little kids doing it is by persistence. your mother sounds like she has many links to child like behaviour and by giving her the attention you are feeding it, and i completely understand why you do. you may feel its embarrasing if she acts like this in public, but people will know shes older than you and will think shes the fool, not you. that goes for everyone who sees her behaviour. i really advise to you to keep trying, it wont be forever that this attitude will continue. she will give up.

take care and good luck.