diff --git a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
index 9388ec8..d104049 100644
--- a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
+++ b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
@@ -51,9 +51,6 @@ protected function setUp() {
    * Tests opening Offcanvas tray by click blocks and elements in the blocks.
    */
   public function testBlocks() {
-    // @todo: re-enable once https://www.drupal.org/node/2830485 is resolved.
-    $this->markTestSkipped('Test skipped due to random failures in DrupalCI, see https://www.drupal.org/node/2830485');
-
     $web_assert = $this->assertSession();
     $blocks = [
       [
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php b/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
index d5156ee..422d7f6 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
@@ -64,6 +64,19 @@ protected function tearDown() {
   }
 
   /**
+   * {@inheritdoc}
+   */
+  protected function drupalGet($path, array $options = array(), array $headers = array()) {
+    $out = parent::drupalGet($path, $options, $headers);
+
+    // When the page has been loaded wait until jQuery is done with all Ajax
+    // activity before any further actions are done on the page.
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
+    return $out;
+  }
+
+  /**
    * Asserts that the element with the given CSS selector is visible.
    *
    * @param string $css_selector
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index 1ab59b6..b756e11 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -906,9 +906,13 @@ protected function submitForm(array $edit, $submit, $form_html_id = NULL) {
     // Ensure that any changes to variables in the other thread are picked up.
     $this->refreshVariables();
 
-    // Log only for JavascriptTestBase tests because for Goutte we log with
-    // ::getResponseLogHandler.
+    // Actions only for JavascriptTestBase.
     if ($this->htmlOutputEnabled && !($this->getSession()->getDriver() instanceof GoutteDriver)) {
+      // Wait on AJAX requests to finish which might have been triggered on load.
+      $this->assertSession()->assertWaitOnAjaxRequest();
+
+      // Log only for JavascriptTestBase tests because for Goutte we log with
+      // ::getResponseLogHandler.
       $out = $this->getSession()->getPage()->getContent();
       $html_output = 'POST request to: ' . $action .
         '<hr />Ending URL: ' . $this->getSession()->getCurrentUrl();