Here’s what you‚ll have to do:
1. Cut 6-7 pieces of strings, each 5-inches long. Tie them together at one end so they look like a string bouquet.

2. To prepare the salt solution: Bring water to a boil in the saucepan. Add salt and few drops of food coloring. Continue adding salt and mixing until no more salt will dissolve into the water. You now have a"supersaturated" solution. You might notice a film of salt crystals forming in a layer on the surface of your solution. At this point, turn off the heat and pour the solution into the plastic container.

3. Submerge the knotted end of your strings into the solution, and arrange strings evenly so that the ends dangle over and around the rim of your container.

4. Leave the container where it won‚t be disturbed. Put a newspaper under it to catch the drippings from the ends of the strings.

5. If you continue adding salt solution when it's evaporated below the knot, you should be able to grow long salt structure In a couple of days you‚ll see that your strings have grown fatter from the crystallizing salt.

Source: www.exploratorium.edu