title: Normalize JSON Object from a multiple column dataframe
body: <p>I am trying to extract some information of a JSON I got from a request, but have some troubles at one point.</p>
  
  <p>As my data is a nested JSON, I first used </p>
  
  <pre><code>df = json_normalize(response)
  </code></pre>
  
  <p>to get the infos into a df. But as a result I get a df, which still has a column with JSON-style information in it, which I can't extract with json_normalize anymore.
  The df looks like:</p>
  
  <pre><code>id    duration     columnA                            
  1     12         [{"A": "600", "B": "30", "C": "50"},{"A": "200", "B": "35", "C": "50"}]  
  2     5          [{"A": "300", "B": "70", "C": "80"},{"A": "400", "B": "76", "C": "90"}]                       
  </code></pre>
  
  <p>But when I am trying</p>
  
  <pre><code>df2 = json_normalize(df['columnA'])
  </code></pre>
  
  <p>I only get an error "AttributeError: 'list' object has no attribute 'values'"</p>
  
  <p>As result I would like to get a df like:</p>
  
  <pre><code>A   B   C
  600 30  50
  200 35  50
  300 70  80
  400 76  90
  </code></pre>