Do you know anyone like this?

I have just returned from a break away with a group of women, all of whom are my relatives.
We vary in ages from late 50s to early 70s.
Over the past few years we have noticed one person in particular cannot seem to stop talking. Even when she knows no one is listening she carries on a conversation anyway. It is as if she is on a loop of needing to say something, even if it not related to whatever the topic is about.
She also constantly interrupts, answers questions you may have asked someone else, and seems oblivious to doing so. At one time someone passed me a phone to show me a photo and this person tried to snatch the phone from my hand, as if the phone had been meant for her.
We have learned to ignore this behaviour and just carry on conversations without her, but I now believe she sometimes does it purpose to wind us up.
In addition to this whenever she is alone (I shared the room next door) she constantly sings to herself, has the TV or radio on, and when she comes into a room she starts singing and talking about whatever she has just heard on the radio.
It is as if she cannot bear any silence at all, and needs to fill (or add to) any lull there might be in conversations.
It really did become on the edge of unbearable for the rest of us, and wonder if it may be something pathological/psychological?
We all love her dearly and she is the most generous and giving person, but we really can't deal with her constant retelling of what she has just doen, or telling us what she is about to do. It never stopped!
Does anyone know anyone else like this and what can we do, if anything?
We sometimes try to make a joke of it but she gets in a huff and thinks we're picking on her, and then does it even more, as if she gets some kind of weird pleasure out of it.
I would appreciate some constructive tips that others may have used in this situation. Although we don't want to exclude her from future holiodays, it is getting to the stage where we don't want to go away again at all.