Because the plant cell has a cellulite cell wall and its function it to protect and keep the overall shape, so when in a hypo tonic solution is added and water enters the cell, the cell wall allows the cell to expand as it can handle pressure. Unlike an animal cell which hasn't got a cell wall only a plasma membrane. The membrane cannot expand like a cell wall and is why they do burst :) .
if we are provided with some vegetables during cooking process. After adding salt it releases water why?