Something causes overclocking on laptop

The first symptom was the laptop fan would run continuously.
To investigate, I started Task Manager and looked at "Performance". Performance shows "Maximum Speed" is 2.40 GHz
But the actual utilization speed was consistently running at 2.85 GHz or thereabouts - running steadily over the rated 2.4 ghz

The fan stopped running and the CPU speed dropped back to normal after I "looked" at Google Backup and Sync in the System Tray.
(I "looked" at a lot of things in Task Manager - trying to figure out what might have been responsible for the overclocking.)

I'm at a loss for what might be causing this. . .the fan has come on a few times since then but by the time I open Task Manager the CPU speeds drops back to below it's maximum.

Any ideas as to what causes overclocking? (I've never experimented with anything to do with CPU performance.)
If it happens again, any ideas as to how to find out what causes the overclocking?

It could be the Intel Turbo Boost technology causing this. You will find this in the BIOS - it is Intel's way of utilising the processor to its best and is perfectly normal.

Exactly.....it's your turbo boost....see here
This is an excerpt from that link.
Performance

• # of Cores2
• # of Threads4
• Processor Base Frequency2.40 GHz
• Max Turbo Frequency3.00 GHz
• Cache4 MB
• Bus Speed5 GT/s DMI2
• TDP15 W
• Configurable TDP-down Frequency600 MHz
• Configurable TDP-down7.5 W