Google is running a test right now that many SEOs will love.  Google is testing a significantly larger font size for headlines in the search results.  This text is very noticeably difference.

Here is how it looks:

Kiran Nagula was the first to spot this test in the search results.

And here is a comparison between the larger headline test and what Google normally displays:

Because Google recently expanded the length of title tags, it means they have a bit more room to work with and test things like this without sacrificing the effectiveness of the titles for searchers.  You can see that the title tags are definitely shorter, but only by a few characters.

I imagine the test CTRs for these are significantly as well.  Especially for those at the top.  But because this test is also affecting the AdWords titles as well, it is possible organic results could end up with a lower CTR if clicks end up focused on ads instead.

This week, Google was also testing larger URLs within the search results too, so it seems this is an areas Google has been testing recently, so I expect we will come across new ones too.

Bing has also recently tested larger headlines in the search results too, a test that is still active today.

This does seem to be a limited test as I was unable to replicate it.