Water shuts off by itself when valve is fully opened

When I open the valve fully at the supply line for my toilet there is a clunk and the water shuts off. If I only open the valve about half way the toilet tank fill up fine, open it any farther and "Clunk" the water turns off. Does anyone have any idea what would cause this? Many thanks in advance.

Did you install a Watts Floodsafe?
They will shut off the water supply when you try to fill a toilet. If so, throw it away and get a normal supply tube for the toilet.

Thank you for your response. We just recently purchased this house, I checked and it does have a Watts Floodsafe, I will replace it with a normal supply tube. I appreciate your help!