Ammonium nitrate, #NH_4NO_3#, is highly soluble in water. Even at #0^@"C"#, you can dissolve more than 100 g of ammonium nitrate in 100 g of water.
In this solubility diagram, ammonium nitrate is represented by a #color(purple)("purple line")#. As you can see, its solubility increases significantly with an increase in temperature.
At #30^@"C"#, you can dissolve close to 250 g of ammonium nitrate in 100 g of water. At #70^@"C"#, you can dissolve close to 470 g per 100 g of water.
You can see a more detailed solubility curve for #NH_4NO_3# here:
http://chemicals.etacude.com/a/more/nh4no3.html
