Could be the variety of potatoe you are using. Try a different variety.

I agree,it could be the variety.try steaming them,instead of boiling,it worked for me,when I used to grow Potato's...

I steam all my vegetables. Carrots cut lengthwise with the potato peeler are easier.(welcome advice from Pamg) New potatoes cut in half are lovely. Slice onions and Cabbage very thinly.
Microwave steamer £8.99 at Argos. Put a little boiling water in the base, give them 9 mins. on High.

Then maybe some salt in the water might prevent this?

Mayan Gold are prone to this so we often cook them very successfully in with a casserol.

years ago I was told to let them rest for 3 days before boiling to prevent this happening. seemed to work.