Here is an interesting test from Google Search. You type in a query, go to the search results and as you scroll through the search results, the search box shows search suggestions. As you can see from the example by Yvo Schaap on Twitter, Google shows various grayed out suggestions to his query.
Here is a GIF of his video in action:
You can see the query was [puzzle games] and as he scrolls, Google adds on suggestions such as “for adults” or “unblocked” or “download” and so on. Pretty neat.
Forum discussion at Twitter.