Ared blood cell is placed in a solution and after a few minutes, it swells and bursts. what type of solution was it, compared to the inside of the cell?

It is a hypotonic solution. Which means, the solution has a higher water potential than the cell cytoplasm.
The cell bursts is because the water molecules flows down the water potential gradient by osmosis, and the cell gains so much water that the cell membrane cannot hold all water and bursts.