Shortly after receiving a degree in painting in 2006, Popper began exploring installation and performing art.
Popper was later commissioned to create a memorial statue dedicated to Nelson Mandela at the Nelson Mandela School of Science and Technology in 2014. The school, set in rural Mvezo in the Eastern Cape, was supported in partnership with Siemens, who commissioned the statue, titled Tree of Wisdom.
Following the 2012 Boom Festival, Popper began to combine stage and production design with large-scale sculptures.
Among Popper's notable festival artworks and installations are Boom Shaman, made for the 2016 edition of Boom Festival, and Reflections at AfrikaBurn in the same year. In 2019, Popper built Anima for the Electric Daisy Carnival (EDC Las Vegas) in the United States, and Modem Swamp for the Modem Festival in Croatia.
In 2018, he debuted Ven a La Luz (Spanish for "come into the light") at the ArtWithMe Festival in Tulum, Mexico. It later became a permanent installation at Ahau Tulum Hotel. This marked the beginning of Popper's transition from temporary festival works to permanent public sculptures.
In 2021, Popper was commissioned by Society Las Olas to create Thrive in downtown Fort Lauderdale and installed Transmission at the Mojave Moon Ranch in Joshua Tree. In the summer of the same year, for the seasonal show at the Bellagio Conservatory in Las Vegas, Popper was invited to create the centrepiece, a sculpture titled Siyanda. The work was later exhibited at 1 Hotel South Beach for Art Basel Miami.
Popper's first exhibition of monumental artworks, Human+Nature, opened at the Morten Arboretum in Chicago in 2021. The exhibition initially consisted of five larger-than-life artworks that reflect on the theme of humans' relationship to the natural world. In 2022, the exhibition was extended for another year, and three pieces were added to the show.