Random Administrative Password Prompt?

Have a look at Activity Monitor (Applications / Utilities /) and select All Processes and sort by Process Name to see what the culprit may be.

image below uses sorting by CPU as an example


Then press CMD+P to print the list and save as PDF and attach it here.

 

Do you have fast user switching enabled?

 

Virus? Its a way of allowing the program to run as your password is needed..

 

Mac Virus/Malware Info by GGJstudios
There are currently no viruses for Mac OS X in public circulation, only a handful of trojans and other malware, which have to be installed manually via entering the administrator password.
The only anti-virus you need to protect your Mac is education and common sense.​

And entering your password during an application installation procedure is giving the installer access to system files and folders. Some kind of malware, most notoriously trojans, are installed that way.