What happens to an animal cell that is placed in a hypotonic solution

water will go from the hypotonic solution to the cell (hypertonic relatively) making the cell to swell eventually ruptures

If you place an animal or a plant cell in a hypertonic solution, the cell shrinks, because it loses water (water moves from a higher concentration inside the cell to a lower concentration outside) ... A single animal cell (like a red blood cell) placed in a hypotonic solution will fill up with water and then burst.