Google continues to put a great deal of effort into mobile search and as such we can expect algorithm updates that will target those who are doing things that hinder user experience for mobile users. Google has just announced that come January 2017, it will be launching a new algorithm update that will target intrusive interstitials. In Google words, “pages where content is not easily accessible to a user on the transition from the mobile search results may not rank as highly.” The three types of interstitials that Google will be penalising: 
Google also shared three interstitials that would not be penalised if handled correctly: 
There's still a good amount of time to get your website into gear, but don't leave this until the last minute. If you're using a popup to collect useful information, start working on a solution that will be accepted by Google. With mobile becoming as dominating as it is and with search still being one of the most used tools on the web, you can't afford to get penalised by this, especially with so much warning!
- Showing a popup that covers the main content, either immediately after the user navigates to a page from the search results, or while they are looking through the page.
- Displaying a standalone interstitial that the user has to dismiss before accessing the main content.
- Using a layout where the above-the-fold portion of the page appears similar to a standalone interstitial, but the original content has been inlined underneath the fold.
Google also shared three interstitials that would not be penalised if handled correctly: - Interstitials that appear to be in response to a legal obligation, such as for cookie usage or for age verification.
- Login dialogs on sites where content is not publicly indexable. For example, this would include private content such as email or unindexable content that is behind a paywall.
- Banners that use a reasonable amount of screen space and are easily dismissible. For example, the app install banners provided by Safari and Chrome are examples of banners that use a reasonable amount of screen space.
There's still a good amount of time to get your website into gear, but don't leave this until the last minute. If you're using a popup to collect useful information, start working on a solution that will be accepted by Google. With mobile becoming as dominating as it is and with search still being one of the most used tools on the web, you can't afford to get penalised by this, especially with so much warning! 