What causes a clicking/crackling sound when walking over a resilient floor?

This can occur when the tile has not conformed properly to the subfloor. When the flooring is installed, it is recommended you acclimate the flooring to the area in which it will be installed. It is also recommended the area be 65°F (18°C) or more. These temperatures will allow the tile to conform when it is laid onto the floor and pressed into place. If the installation area is cold, and/or the tile is cold, the tile will not conform properly. When you walk on tile, you are pushing it down into the adhesive, and if the tile is not conformed, you are pushing it into contact with the adhesive which causes the clicking/crackling sound. To fix this, you can usually heat the area for at least a day, and then roll the tile using a 100-pound roller.