<div class="button">
  <p>Button</p>
  <figure>
    <img src="http://lorempixel.com/400/300/" width="400" height="300" alt="photo">
    </fugure>
</div>
<div>
  <p><a href="https://www.sitepoint.com/community/t/trying-to-show-image-in-popup-box-when-i-hover-over-a-button/232770?u=sama74">https://www.sitepoint.com/community/t/trying-to-show-image-in-popup-box-when-i-hover-over-a-button/232770?u=sama74</a></p>
</div>

.button {
  position: relative;
}

.button p {
  display: inline-block;
  background: blue;
  color: #fff;
  padding: 0.4em 0.6em;
  font-size: 1.3em;
  border-radius: 1em;
}

.button figure {
  display: none;
  position: absolute;
  top: 2em;
  left: 1em;
  padding: 0;
  margin: 0;
  border: 5px solid #fd0;
  background: #fd0;
  border-radius: 1em;
}

.button img {
  display: block;
  border-radius: 0.8em;
  max-width: 100%;
  height: auto;
}

.button:focus figure,
.button:hover figure {
  display: block;
}
.button:focus p,
.button:hover p {
  background: red;
}