Download and install Audacity 1.2.6, the latest stable version of this open source freeware audio processing software. It is available from audacity.sourceforge.net or from CNET's Download.com.
Download the LADSPA plug-in pack for Audacity, available on either of the previously mentioned websites. This pack of plug-ins is tested safe for use with Audacity for Mac or Windows, and seriously extends the program's functionality for removing pops, clicks and other noise from your audio tracks. Run the file you just downloaded, which will add the plug-ins' functionality into Audacity.
Load your song or sample that has become infected by pops, clicks or other noise and try the "Noise Removal" plug-in near the top of the "Effects" tab. Audacity will ask for a section of the song that contains pops to be removed. Find a section of the audio track where you hear audible pops, select it and run the noise removal.
Experiment with different noise removal levels within the plug-in until the pops or clicks are gone from your audio track, while causing the absolute minimum amount of distortion to the track.
Scroll down the list of plug-ins that you installed and find the "Gate" plug-in. This is what's called a noise gate, and will help in removing pops from your audio track that can come by combining samples or parts together. This should help remove any pops that the other plug-in left behind.
Run the "Quick Mix" under the "Project" tab, which will help restore the audio track to more normal levels. If you have the know-how, try some of the manual EQ filters instead under the "Effects" tab. Your audio track should now be free from pops and clicks and have a nice, clean, even sound.