Today, Google published an article on how improvements to search results have been rolled out, when quotation marks are used as a part of the search term.
Initially, the usage of quotation marks allowed you to search for a specific word or phrase, and the results will filter out all other options (e.g. "caesar salad" will not show results for Julius Caesar). The latest updates that Google introduced improves the snippets that are displayed when you are shown the search results.
These snippets often show a preview of the page that it is linking to, but previously would just show a select section of the page. When quotation marks are used in the search, the snippet will now display where in the page that word or phrase is located as shown in the image below.
The reason behind not doing this before, Google says, is that "the quoted material appears in areas of a document that don't lend themselves to creating helpful snippets". But the feedback from people who use these searches showed that actually displaying the quoted phrase in the snippet was valued and found to be useful.
One caveat that Google has highlighted is that quoted searches do not work for local results where listings would be shown with a map, and this is something that the company will be looking at in the future.