High Quality Content by WIKIPEDIA articles! Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to move into the cell. It occurs in a hypotonic environment, where water diffuses into the cell and causes its volume to increase. If the volume of water exceeds the cell membrane`s capacity then the cell will burst. The cell will only burst if the cell is an animal cell and it will only expand if it is a plant cell.